1. Field of the Invention
The present invention relates to a communication system for performing the communication of character code data, image data, or the like.
2. Related Background Art
In recent years, in the field of office automation, there has been put into practical use in the market an apparatus, i.e., mixed apparatus, such that image information (such as figures, graphics, photographs, or the like) is electronically processed, or character information to be processed by a word processor or the like and the image information are edited and processed as a document, and this document is communicated with another apparatus through a communication network or the like.
In such an apparatus, the image information is input from an input device such as an image scanner or the like, the character information is input from an input device such as a keyboard, and this information is stored in image memories or the and displayed by a display device such as a CRT and edited by use of an input device such as a pointing device, a keyboard, or the like. The character information in the document edited in this manner is transmitted by codes and the image information is compressed and thereafter transmitted to another apparatus through a communication unit.
The receiving apparatus which receives the document temporarily stores the received document in an auxiliary memory unit and informs the operator of the reception of the document by a message displayed by an LED, CRT, or the like. The operator looks at this message and activates the utility to output the received document.
The utility to output the received document stores the character information as bit patterns in an image memory by use of a character generator. On the other hand, the image information is expanded by use of a compression/expansion unit and thereafter stored in the image memory. After all of the document information of one page is stored, the information in the image memory is printed and output on a recording paper which is set in an output device such as a laser beam printer or the like.
In the foregoing apparatus, in order to edit the received document or to transmit the received document to another communication terminal, the received document is temporarily stored in a preservation storage unit and is printed and output only by an instruction of the operator.
Therefore, in the foregoing conventional apparatus, there is a problem such that even in the case of a document which must be promptly sent from the transmission side, it is stored and held on the reception side. On the other hand, there is also a possibility such that while a document is being stored, an abnormality occurs in the hardware, so that the document is deleted. Further, there is a problem such that when the rest of memory does not exist in the memory unit on the reception side, the reception is refused.
On the other hand, in such an apparatus, if there is no vacancy of the memory in the auxiliary memory unit on the reception side, the communication with the transmission side is forcedly interrupted. In this case, in order to enable the transmission side to know the state in which the communication can be restarted since a vacancy is formed in the auxiliary memory unit, the transmission side must monitor the reception side. On the other hand, there is a problem such that in order to enable the transmission side to promptly know the state in which the communication to the reception side can be restarted, the reception side must be always monitored.
On the other hand, the foregoing apparatus can select whether the received document stored in the memory is printed by a printer or displayed by a display device such as a CRT or the like on the basis of an instruction of the operator. In such an apparatus, if the memory such as a hard disc device or the like is out of order during the operation, not only the local operation such as copy, edition, or the like and the transmitting operation but also the receiving operation cannot be executed.
In this case, even if the local operation and the transmitting operation are executed after the failure of a memory such as a hard disc device or the like was repaired, a problem will hardly occur.
However, if information was transmitted from a distant apparatus when the memory such as a hard disc device or the like is out of order, it cannot be received at all, so that a problem occurs. In particular, this causes a serious problem if the transmitted document is important.
On the other hand, in the foregoing conventional apparatus, it is possible to delete only the received document which was printed by the printer or the received document which was output to the display device and which was temporarily stored and held in the memory such as a hard disc device or the like.
Therefore, when the operator is directly operating the apparatus, every occurrence of the reception of a document, or when a predetermined amount of a document has been stored in the hard disc device or the like, the operator instructs a printing. After completion of the printing, the printed received document is enabled to be deleted from the memory. With this constitution, the impossibility of reception due to the lack of memory can be avoided.
However, if the document was continuously received without being printed and the received document is stored and held in the hard disc device or the like, the impossibility of the reception due to the lack of memory such as a hard disc or the like occurs. In particular, there is a problem such that when the apparatus is set in the automatic receiving mode for 24 hours, if a large amount of documents were received in the unmanned operating mode at night or the like, the impossibility of reception due to the lack of memory in the hard disc or the like occurs.
As communication systems using a reception memory of a large memory capacity, the applicant of the present invention has so far proposed U.S. patent application Ser. No. 873,541, and U.S. Pat. Nos. 4,622,594, 4,598,323, 4,712,139, 4,679,903, 4,805,135, 4,706,127, 4,789,900, 4,682,186, 4,677,649, and 4,717,967, and the like.
However, the applicant of the present invention has not proposed so far a communication system which can solve the foregoing problems.